The protein c anticoagulant is important in the regulation of hemostasis and thrombosis. Previous work performed by our group indicates that the fetal PC molecule may be dysfunctional compared to the adult molecule and thereby contribute to the increased incidence of thrombosis seen in the sick preterm and term infant. We propose to investigate and compare the molecular, structural, anticoagulant, and profibrinolytic properties of fetal and adult PC in order to learn more about the fetal PC system.